1. Field of the Invention
This invention relates to an electronic circuit for a speakerphone. More specifically, the invention relates to such a circuit which permits full duplexing in one unit with microphone and speaker being disposed in fixed positions relative to one another and in close proximity to one another.
2. Description of the Prior Art
In available speakerphones with full duplexing, the receivers have to be arranged so that they are movable relative to the transmitter. This is necessary to overcome effects of acoustic coupling which causes large amounts of squeal arising out of acoustic feedback from the microphone to the speaker circuits. In such units, acoustic coupling can be eliminated by physically adjusting the positions of the speaker and the microphone relative to each other.
However, it is inconvenient to have to move the elements relative to one another, and it is also inconvenient to have to have two separate elements located on, for example, a desk, as this takes up an inordinate amount of space. In addition, it is uncomfortable to be subjected to the squealing noise before a physical adjustment is made.